Hybrid parallel

[dexus]

Nice test @PGia, thanks!

For some reason I didnt consider closed polylines in the _checkOffset function, so I added an extra check there.

Should work as expected now:

 

Not sure about the short corner. The lines are so narrow the centerline is pushed back out of the point.

Seems to be logical to me but it does feel intuitive.

 

Narrow indents don't get much love from the centerline. So "inlets" don't have enough influence on the shape of the line.

What would the expected result be? Below makes sense since there is not enough space to go into the indent.

Or are you maybe something like this where the line splits and goes into the hole:

 

Edited Thursday at 01:28 PM by dexus

[dexus]

I did some more tests today and found that when the end segments were parallel, they didn't get added to the line.

So I added support for that. This one was easy because the _cornerOffset function already checks for parallel segments and I just had to add a flag to inform the offset loop. 

 

 

And I found another example which it has a hard time on with concentric arcs, attached below.

But that will be for another day since I have no more time for that this week.

 

AxisExple3.dxf

Edited Friday at 02:11 PM by dexus

[PGia]

I think the real-world situation may be more complex than what we’ve seen here so far.

I took a look at the links that @SLW210 attached and decided to test the Lisp codes proposed up to this point.

I looked through my drawings for something that could serve as an example for this problem, but it was like looking for a needle in a haystack.
So, in the end, I decided to look for something in the real world that clearly corresponds to this issue — something like this:

 

So I drew those margins and tested all the codes that have appeared in this thread so far.
The result was… this!

 

In the drawing, you can see the ones that managed to reach the end.
However, the codes by BIGAL, GP_, GLAVCVS, and MarkoRibar couldn't even do that.

Here’s the drawing

AxisExple4.dwg

 

Edited 19 hours ago by PGia

[dexus]

Hi @PGia, wow, you managed to find another example that fails. Good stress testing!

 

The reason mine fails is because it ignores the offset lines that are split in two or more parts.

But some of the parts are still be usable and should be used.

I looked into fixing this and managed to add those lines, but this resulted in some other problems so I didn't update the code on the earlier post yet.

 

The zigzag problem is coming back on your example. The result below.

I really need to find a solution for that, but it looks like I might have to use a path finding algorithm which would slow down the code a lot. Sorting the points by distance on the offset line is not enough anymore.

[SLW210]

IIRC, those are tough to manage on GIS programs with Add-ons made with Python, .NET, etc.

 

Remember, real rivers/roads/ROWs have curves and organic shapes, not just straight lines.

 

I did see some information on how to tackle those, hopefully it can be worked out, but don't expect perfection.

 

As I mentioned, from what my daughter said and what I've seen in various related forums, the GIS pros are using whatever program and add-ons they can to get the bulk of it and cleaning up and filling in manually.

 

Most that are doing those shapes want the main channel center, if needed I would ignore the very wide sections and side pieces and get those as center lines running back to the main channel separately.

 

As your example shows, it would take separate polylines, so it will need to account for those sections and then ran again on the offshoots.

 

You still haven't answered all of the questions asked.

 

What type of work are you doing? What you have posted looks to be Civil and/or GIS work.

 

I'll try some more on this when I can, I have also looked at some different shortest path codes, the last example is way over my head in LISP, I'll concentrate on the previous examples then try to run just the main channel on the last example .dwg.

 

I have a full slate at work again today, but I'll try to jump back on this when I get some things out of the way.

 

Home time is limited, but I'll try to get back on this with QGIS solution, I may see if my daughter's coworkers want to take a shot at these.